VTS Operations
There are two principle types of Vessel Traffic Service; an Information Service (INS) and a Traffic Organisation Service (TOS). These are defined in IALA Guideline 1089. In addition, there is the option that a VTS may provide a Navigational Assistance service to arriving and departing ships. The choice of either an INS or a TOS VTS will be based on the results of the risk analysis of the VTS Area with higher risk situations adopting a TOS based on the level of advice and / or instruction that vessels may need to safely navigate the VTS Area.
IMO resolution A.918 (Standard Marine Communication Phrases - SMCP) provides guidance on the way that VTS information should be passed to the crew on board an incoming vessel. As crews are drawn from many different nationalities and cultures, different crews may interpret the information given by a VTS in different ways and the IMO resolution A.918 aims to ensure that the standard marine phrases all have a common understanding. The SMCP includes Message Markers which are intended to precede the information provided by a VTS operator. The eight Message Markers are: Information; Warning; Advice; Instruction; Question; Answer; Request; Intention. Clearly some of these message markers are intended for use by a TOS, but an INS may use all of these Message Markers if situations develop that demand a more interventionist course of action. This does mean that the precise boundary of each of there types of service is unclear.
IALA distributed a questionnaire recently that provided a useful view of how VTS has been implemented. It noted that many VTS Authorities that had declared an Information Service did give Instructions to ships. But there was also a high percentage that did not give Instructions. This section will aim to translate the types of service from Operational Requirements to Technical Requirements.
Information Service (INS)
An Information Service is defined as a VTS that provides essential and timely information to assist the on-board decision making process. This means that VTS operators can inform the master of a vessel about the situation he can expect to encounter within the VTS Area but the VTS may not have the experience to advise on any specific course of action that should be taken.
From a VTS system point of view, the VTS Operator within an Information Service (INS) needs the facilities to monitor the operational situation relating to all maritime activity within the VTS area and requires facilities to communicate with vessels by VHF radio. Decision Support facilities may not be a necessary part of an Information Service, but the full recording of all activity remains essential and performance measurement should still be a desirable feature.
Technical Requirements
The technical requirements for an INS VTS are therefore as follows:
- Situational Awareness
- Voice Communications
- Recording facilities
Traffic Organisation Service (TOS)
A Traffic Organisational Service is defined as a service to provide safe and efficient movement of traffic and to identify and manage potentially dangerous traffic situations. The Traffic Organisation Service provides all the services of an Information Service (INS) but may also advise, instruct or exercise authority to direct movements. In such cases, the Traffic Organisational Service is likely to be provided by fully trained operators who will use the full set of message markers in their communication with vessels within the VTS area.
From a VTS system point of view, it is clear that the VTS Operator in a TOS environment needs more functionality from his VTS system that the VTS Operator in the INS environment. He will need tools that help him to identify risks of collision, risks of grounding, speed monitoring tools, fairway monitoring and possible anchorage monitoring. So there is a clear difference between the functionality required to support a TOS VTS and the functionality required to support an INS VTS.
Technical Requirements
The technical requirements for an TOS VTS are therefore as follows:
- Situational Awareness
- Voice Communications
- Collision Avoidance
- Decision Support Tools
- Near Miss Analysis
- Recording facilities
Navigation Assistance Service (NAS)
A Navigational Assistance Service is provided in addition to an Information Service and / or a Traffic Organisational Service. It is provided at the request of a vessel or is sometimes is sometimes initiated by the VTS should a difficult traffic situation be developing.
Technical Requirements
The technical requirements for an NAS VTS are therefore as follows:
- Remote Situational Awareness
- Voice Communications
- Decision Support Tools
- Recording facilities